Frequently, horror movies send some useful idiots to a remote location, and then hack them up victim by victim. But what might happen if one of the potential corpses had some self-defense savvy?

Nothing especially surprising, as “You’re Next” demonstrates. But the latest genre exercise from slasher-flick prodigy Adam Wingard (“A Horrible Way to Die”) is at times bloodily entertaining. And if the central plot twist isn’t all that clever, at least the movie offers some motivation for its mayhem.

That’s not apparent at first. In the prologue, two residents of a vacation home are butchered for no apparent reason by black-suited berserkers who wear animal masks. Wingard and scripter Simon Barrett redeem this sequence with a sly joke: Just before she’s killed, one of the victims puts the Dwight Twilley Band’s “Looking for the Magic” on repeat. It plays for the rest of the movie, although not always within earshot. (Nice way to keep the music budget down.)

The major bloodbath takes place just up the road at another vacation home, a fake-Tudor mansion owned by a couple whose wealth comes from, heh heh, defense contracting. Paul and Aubrey (Rob Moran and Barbara Crampton) have invited their four adult children (and their significant others) for a 35th anniversary celebration. The weapons mogul didn’t think to bring drones, rocket-propelled grenades or even a starter pistol with him.

Most of these characters are disagreeable, so the prospect of their imminent demise isn’t too upsetting. The movie doesn’t dawdle in revealing the houseguest who’s going to put up a fight. It waits a while longer before identifying the characters who are not merely obnoxious, but altogether monstrous.

That wait means enduring too many shock cuts and gory assaults, as well as a surfeit of creaks, squeals and droning bass notes. Also tiresome are repeated scenes in which the characters discuss what strategy is most likely to prolong their existences — and then promptly do the opposite.

Once the predators become prey, however, “You’re Next” becomes livelier. Also funnier, although the jokes tend toward the ghastly. Still, it’s a nice switch to see a one-by-one murder spree in which an inexorable killer is fighting to save rather than end lives. Even if that effort is not particularly successful.